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Question #45427
The Question
During embryogenesis, impaired differentiation of specific endodermal stem cells can lead to thyroid dysgenesis and a subsequent lack of thyroxine () in the neonate. Which of the following statements correctly identifies the physiological consequence of this defect and differentiates it from a somatotropin (Growth Hormone) deficiency?
Options
- A.
It results in cretinism, characterized by arrested neuronal branching and delayed epiphyseal ossification, leading to mental retardation and stunted growth; whereas somatotropin deficiency causes proportionate dwarfism without cognitive impairment.
- B.
It results in myxedema, characterized by the accumulation of interstitial fluid and deaf-mutism, whereas somatotropin deficiency causes disproportionate dwarfism with a low intelligence quotient.
- C.
It causes a failure in basal metabolic rate regulation and accelerated epiphyseal plate closure, leading to stunted growth with normal intelligence, unlike somatotropin deficiency.
- D.
It leads to the hypersecretion of Thyroid Stimulating Hormone (TSH) which directly inhibits developing neurons and osteoblasts, causing cretinism, whereas somatotropin deficiency is TSH-independent.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Differentiation of Stem Cells|Thyroid_Folliculogenesis|Morphogenesis
Why This Question Is Tricky
Common Mistakes
Functional Overlap & Age-Specific Pathology Trap: Students often confuse the types of dwarfism (Cretinism vs Pituitary Dwarfism) and the age-specific manifestations of hypothyroidism (Cretinism in infants vs Myxedema in adults).
The conceptual pivot is recognizing that thyroid hormones uniquely govern both somatic growth AND central nervous system development, whereas Growth Hormone primarily governs somatic growth.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Thyroid Hormone Synthesis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |